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SPCE: Sound Propagation Comparison Exercise

Bertagnolio, Franck; Bass, Jeremy ; Drobietz, Roger ; Blodau, Tomas ; Søndergaard, Bo ; Bak, Christian;Aagaard Madsen , Helge

Publication date:2014

Link back to DTU Orbit

Citation (APA):Bertagnolio, F. (Author), Bass, J. (Author), Drobietz, R. (Author), Blodau, T. (Author), Søndergaard, B. (Author),Bak, C. (Author), & Aagaard Madsen , H. (Author). (2014). SPCE: Sound Propagation Comparison Exercise.Sound/Visual production (digital)

https://orbit.dtu.dk/en/publications/234b55da-89ce-41a5-8a87-fb1a91154aa0

DTU Wind Energy, Technical University of DenmarkEWEA Technology Workshop:

Wind Turbine Sound 2014Malmö, Dec. 2014

SPCE: Sound PropagationComparison Exercise

Wind Turbine Sound 2014 Organizing Committee

2 DTU Wind Energy, Technical University of DenmarkEWEA Technology Workshop:


Comparison Exercise

➢ EWEA organized previous comparison exercises 2011 CREYAP Part I 2013 CREYAP Part II 2013 Offshore CREYAP Part I

http://www.ewea.org/comparison-exercises/

➢ Idea: Perform similar exercise for wind turbine sound propagationwind turbine sound propagation

Sound Propagation Comparison Exercise = SPCE




WIND TURBINE NOISEPerception of

sound byreceiver

Propagation ofsound

Wind turbinenoise

Noise generationmechanisms

Atmospheric conditions,Orography, Vegetation,Refraction, Diffraction

More subjective,Sensitivity

of individual,Quality of noise,Home insulation

As it can be measuredin the direct vicinityof the wind turbine

& As used for WT noise assessment

Aerodynamic and/or

Mechanical noise



The Physics of Sound Propagation

➢ Atmospheric conditions Stratification Wind direction Wind shear/veer Turbulence

➢ Boundary conditions Topography Vegetation / Water Man-made structures

➢ Sound intrinsic properties Different frequencies travel differently AM

Influenced by:

… make predictionsdifficult!!!



Prediction Methods

➢ Analytic formula Attenuation as fct. of distance ...

➢ Simplified physics Ray method Vegetation / Water Man-made structures

➢ Partial differential eqns. Parabolic eqns. method CAA

From very simple to advanced:

Different hypotheses and implementations

may yieldvery different results!very different results!



Prediction Methods Results

Sensivity of the results to:➢ Local wind turbine site conditions

➢ Model accuracy

➢ Various standards/norms for quantifying noise immission levelsquantifying noise immission levels

➢ User itself!!! Experience Interpretation of the local site conditions Interpretation of the noise sources (corrections/uncertainties) Interpretation of the results (post-calculation corrections)



Comparison Exercise Ojectives

➢ Evaluate influence of above parameters

➢ Not a parameter study!➔ Rather study influence of parameters relatively to the

different methods

➢ Evaluate models with respect to each other

➢ How same type of models can differ

➢ How different users may yield different results

➢ Final goal:➔ Provide guidelines/regulations for using

sound propagation prediction methods



Comparison Exercise: Test Cases

➢ Inputs (provided as test cases definition) 1 landscape with different features in 4 cardinal directions:

• Flat/hilly• Surface cover• Sheltered/non-sheltered houses

For different atmospheric conditions (?) For different wind speeds & directions Turbine sound data:

• Location and hub height• Overall sound levels and/or 1/3 oct. band spectra• Uncertainty• AM – Effect of AM at source on far-field noise (?)

➢ Output Noise



Comparison Exercise: Test Cases

➢ Outputs (returned by the participants)

Noise Levels (Leq, L90, spectra…) At specified locations ranging from 300 to 2000m At specified heights

➔ Using provided template for the results Easier post-processing and analysis of the “many” participants data!

➢ Participants also to provide - Survey form: Organisation name and person responsible Details on noise propagation model Use of post-calculation corrections (if so, why?) Participants welcome to use different prediction methods/models and explain differences



Comparison Exercise: Procedure

➢ Participants perform calculations and send back results template and survey form

Results in pre-defined template Description of method used, in-house or commercial code, user details

➢ EWEA representative collects all data Data made anonymous

➢ DTU Wind Energy performs data analysis Provide a report compiling results and conclusions Presentation at a later EWEA event



Comparison Exercise: Timeline

➢ Call to participant (~ February/March) Test-cases definition and result templates sent to those interested in participating


➢ Deadline for participants returning results template & survey (~ August/September)

➢ Presentation of the results analysis at EWEA 2015 Annual Event , Paris 17/20 November 2015



Discussion...

➢ What is your opinion on this exercise?

➢ Suggestions concerning the test-cases...

➢ Suggestions concerning the procedure...

spce: sound propagation comparison exercise · 7 dtu wind energy, technical university of denmark...

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